Beting Forestry Univ.June 11.2011 Formation and dynamies of the alpime treelime Prof.Dr.Mai-He Li )第382海 E-mad maih Treelines 全球高山林线研究简史 Exposure treeline(on coasts,isolated mountains) 形态描述阶段(1920年代之前) (Koppen,Brockmann-Jerosch,Daniker) Wet treeline(on the margins of muskegs bogs) Dry treeline (desert treeline) 现代实验生态研究阶段(1930年代-1970年代) Arctic/Antarctic treeline (Pisek,Larcher,Tranquillini) Cold treeline Alpine treeline 全球变化下的高山林线研究阶段(1980年代始) (Tinner,Korner,Dullinger) Upper treeline vs.low treeline LiMH and KraeuchiN(2005)J Sichan For Technd2664 Rsgaone2o0-2z0mas
1 Beijing Forestry Univ. June 11, 2011 Tree Ecophysiology Group Swiss Federal Research Institute WSL Prof. Dr. Mai-He Li E-mail: maihe.li@wsl.ch Treelines • Exposure treeline (on coasts, isolated mountains) • Wet treeline (on the margins of muskegs & bogs) • Dry treeline (desert treeline) Upper treeline vs. low treeline Arctic / Antarctic treeline • Cold treeline Alpine treeline 全球高山林线研究简史 形态描述阶段 (1920年代之前) (Köppen, Brockmann-Jerosch, Däniker) 现代实验生态研究阶段 (1930年代-1970年代) (Pisek, Larcher, Tranquillini) 全球变化下的高山林线研究阶段(1980年代始) (Tinner, Körner, Dullinger) Li MH and Kraeuchi N (2005) J Sichuan For Sci & Technol 26, 36-42 Pinus cembra treeline ecotone (2100 – 2200 m a.s.l.) in Valais, Switzerland
Alpine zone 0 Morare forest 144 2
2 Picea purpurea treeline ecotone (4100 – 4300 m a.s.l.) in Huang-Long, Sichuan Ch Koerner, J Paulsen 2004 Tree height 2 or 3 m Kyi Chu, North of Lhasa 29°42‘ N, 96°45 ‘ E Miehe et al. 2007. Mountain Res. & Develop. 27, 169-173 Factors affecting trees at the alpine treelines Holtmeier & Broll, 2009. Polarforschung 79, 139-153
Environmental conditions 200c vs.high elevations) 50t Lowelevation High olevation 100c 500 10 14 18 20 Soil unde alpine than under treeline trees Treeline:Energy flux in forests and low vegetation JFMAM寸寸ASOND JFMAMJ AS ON D warm Aglobal mean treeline The alpine treeline position is very closely correlated to the 10C e.p isotherm for the warmest month 2。 The temperature at the alpine 2 treelines varied from 6 to 13C (+500 m in treeline elevation) %8083W高96
3 Low elevation High elevation Mean temperature High Low Diurnal variation in temperature Low High Growing season length Long Short Environmental conditions (low elevations vs. high elevations) g g Precipitation Low High Wind Low High Soil quality High Low Total ecosystem energy High Low Radiation intensity when clear Low High UV intensity Low High Partial pressure of CO2 High Low 1000 1500 2000 Altitude (m) below forest below grassland Nothofagus forests, South Island, New Zealand, in midsummer 0 500 8 10 12 14 16 18 Temperature at 20 cm soil depth (°C) below forest Körner et al. (1986), triangle Greer (1978), in: Ch Körner (2003) Alpine plant life. Springer, Berlin. Soil under alpine vegetation is warmer than under treeline trees rature at 10 cm soil depth (°C) Vaccinium heath (420 m) Treeline (420 m) N-Sweden Abisko 68° N Swiss Alps Valais, Furka 46° N Treeline (2240 m) Alpine grassland (2500 m) -5 0 5 10 15 Daily mean root zone tempe J J F M M A A J J S O N D Himalaya Langtang 28° N Alpine grassland (4010 m) Treeline (3980 m) Alpine grassland (4000 m) Mexico Iztlaccihuatl 19° N Treeline (4000 m) 5 -5 0 5 10 15 J J F M M A A J J S O N D Treeline: Energy flux in forests and low vegetation 15 °C 8 -10 °C warm cool The alpine treeline position is very closely correlated to the 10°C isotherm for the warmest month The temperature at the alpine treelines varied from 6 to 13°C (±500 m in treeline elevation) Koeppen 1923; Aulitzky 1961 Wu 1983; Oshawa 1990 n=2 1 12 2 2 6 3 2 4 6 8 n temperature, T (°C) G (d) 6.7 ± 0.8 °C G T A global mean of 6.7 °C at treeline 0 2 4 Seasonal mean 70 60 50 40 30 20 10 0 10 20 30 40 Latitude (°C) 0 100 200 300 Growing period N S G Ch Körner, J Paulsen (2004) J Biogeogr 31:713 Ch Körner, J Paulsen (2004) J Biogeogr 31:713-732
Treeline formation Environmental explanation of treeline (1)The stress hypothesis (2)The maturation time hypothesis (3)The disturbance hypothesis (4)The reproduction/germination Loca2ogmaomgera hypothesis Biological explanation of treeline 1.The stress hypothesis (5)The carbon balance hypothesis (6)The growth limitation hypothesis impair tree growth Radiation 2.The maturation time hypothesis stress Maturation of leaves, shoots,fruits,and bud 4
4 Treeline Treeline formation formation Global drivers 'general principle' Regional drivers general principle 'modulation modulation' General physioecological explanation Local environmental explanations (1) The stress hypothesis (2) The maturation time hypothesis (3) The disturbance hypothesis Environmental explanation of treeline ( ) y (4) The reproduction/germination hypothesis Körner Ch (1998) Oecologia 115:445 Li MH, Krauchi N (2005) J.S.For.Tech.26, 36-42 Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 (5) The carbon balance hypothesis (6) The growth limitation hypothesis Biological explanation of treeline Körner Ch (1998) Oecologia 115:445 Li MH, Krauchi N (2005) J.S.For.Tech.26, 36-42 Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 1. The stress hypothesis • Repeated damage by freezing, frost desiccation or phototoxic effects impair tree growth Tranquillini, W. 1979. Physiological Ecology of the Alpine Timberline Radiation stress Evergreen Pinus cembra has a hard time in late winter, when exposed to bright sun with zero photosynthetic activity due to cold temperatures. Other species as for instance Larix decidua (in the background) avoid such problems by shedding their leaves in autumn. With this strategy, they can grow in the coldest place on earth, in sub-polar western Siberia. Maturation of leaves, shoots, fruits, and buds 2. The maturation time hypothesis e.g. seed maturation of Pinus sylvestris needs at least 600 – 890 GDD (growing degree-days >5°C) Odum 1979 In late summer, an early frost can prevent the completion of reproduction
3.The disturbance hypothesis Wind effects on plant growth c dam Wind effects on local treeline formation Avalanches on and the char Mortality mal disturbances 5
5 Mechanic damage by wind, ice blasting, snow break and avalanches, fire…… 3. The disturbance hypothesis Animal disturbances such as herbivory: Fungal pathogens; Man-made impacts such as grazing Tranquillini, W. 1979. Physiological Ecology of the Alpine Timberline Helianthus annuus Wind effects on plant growth Martin & Clements, 1935, Plant Physiol. 10, 613-636 0 5 10 15 • The altitudinal position and the character of the treeline may be winddetermined, i.e. the altitudinal limit of tree growth is lowered by strong and regular winds. Wind effects on local treeline formation Rocky Mountains National Park Avalanches Animal disturbances Mortality Fate of seedlings of Picea abies (Norway spruce) in a subalpine spruce forest after the first winter. Most individuals were killed by the Herpotrichia nigra (snow mould) and by mice. A dense web of Herpotrichia nigra hyphae around a low branch of small spruce. The parasitic fungus grows preferably in air pockets around branches in the snow
Human impacts:deforestation 4.The reproduction hypothesis Pollination,pollen tube growth. seed development,seed dispersal,germination and seedling establishment Seed weight with altitude SE() : 0.10-n m 5.Growth limitation 6.Carbon limitation Source limitation hypothesis: Tree growth is considered source limited Growth when carbon assimilation through photo- Photosynthesis Growth Sink limitation hypothesis: "Sink"driven "Source"driven Supply driver owth,but ental conditions. 6
6 Human impacts: deforestation Cleared woodland for settlements (Avers valley, 2000m, Grisons, Switzerland). Pollination, pollen tube growth, seed development, seed 4.The reproduction hypothesis dispersal, germination and seedling establishment Tranquillini, W. 1979. Physiological Ecology of the Alpine Timberline Seed weight with altitude Baker (1972) argued that alpine plants have smaller seeds, because they can devote fewer resources to sexual reproduction than lowland plants due to the short growing season. Decreasing weight per seed with increasing altitude in 14 populations of Saxifraga oppositifolia (left) and eleven populations of Scabiosa lucida (right) (Plüss & Stöcklin). Krummholz Seedlings Dead individuals Tree species line Adults Camarero & Gutierrez (2002) Plant ecology 162: 247 Timberline 5. Growth 5. Growth limitation limitation Ph t th i Growth Photosynthesis Growth 6. Carbon limitation limitation Photosynthesis “Sink“ driven “Demand“ driven Growth “Source“ driven “Supply“ driven Körner Ch (1998) Oecologia 115:445 Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 Source limitation hypothesis: Tree growth is considered source limited when carbon assimilation through photosynthesis is insufficient to meet growth requirements. Sink limitation hypothesis: Trees are considered carbon sink limited when there is an abundant supply of the resources necessary to support growth, but growth itself is directly limited by environmental conditions
echange wit而 edle nit a 02 LowE O.K2 07E1.10 1.080.400.3928 Nitrogen contents (treeline trees lower elevation trees) 出l80aeta2a2a29.1387 P0.05 P<005 Low Md Low Pe0.0 0.og 出m28m82a12a9.13a An overall trend in NSC 14014.7 480 1461.616.a7刀53能0.9023447935524 10. 54 .53 A winter C a07 163 10.2 LI MH et aL 200 cel&E白 7
7 Gas exchange with altitude Acaena cylindrostachya Maximum CO2 assimilation rates 4200 m: 3.9 µ mol/m2 s 3550 m: 5.2 µ mol/m2 s 2900 m: 9.0 µ mol/m2 s Cabrera HM et al. 1998, Oecologia 114, 145-152 Senecio formosus 4200 m: 3.6 µ mol/m2 s 3550 m: 5.8 µ mol/m2 s 2900 m: 7.5 µ mol/m2 s Overall N across tissues N in source N in sink Source-sink ratio April July April July April July April July Three treeline cases combined Treeline Trees 0.93 0.88 1.23 1.19 0.48 0.40 2.6 3.0 Whether the needle nitrogen associated with photo Whether the needle nitrogen associated with photosynthesis (carbon gain) determines the alpine treeline? Low E trees 0.82 0.78 1.10 1.04 0.40 0.39 2.8 2.7 F(df) 24.54 (1,89) 10.07 (1,89) 14.27 (1,53) 9.28 (1,53) 14.74 (1,35) 0.85 (1,35) p lower elevation trees) Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 P<0.05 P<0.05 Shade needles Sun needles Richardson AD. 2004 Plant & Soil 260, 291-299 P<0.05 P<0.05 Abies balsamea Picea rubens 5 10 15 20 25 30 / NSC concentration (% d.m.) Sugars Starch 1-yr-old needles Stem wood Fine roots * A * ** * * * 2-yr-old needles 3-yr-old needles Carbon shortage? - Yes! 0 5 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m 3800m 3400m April July April July April July April July April July Elevations of trees and sampling time Starch / Sugars a b a a a a a a b b b b b b A B Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 Picea balfouriana var. hirtella Soluble sugars Starch NSC April July April July April July Three treeline cases combined (Lower E trees = lower elevation trees) Treeline trees 11.09 10.51 3.61 4.19 14.70 14.70 An overall trend in NSC Lower E trees 10.66 10.37 4.77 4.55 15.43 14.91 F1,89 3.53 0.24 31.00 1.35 6.80 0.31 p 0.07 0.63 <0.001 0.25 0.011 0.58 Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 A winter C A winter C-shortage shortage Glucose Fructose Sucrose Starch Total soluble sugars Non structural carbohydrate content (mg/g dry mass) of roots of Abies georgei growing at altitudes of 4330 (treeline) and 3480 m a.s.l., Sergyemla Mountain, Tibet 3480 m 14.96±1.86 14.99±1.73 5.66±0.90 42.33±4.79 35.62±4.13 4330 m 8.29±0.89 7.81±0.81 2.73±0.56 37.38±2.62 18.84±2.13 P 0.002 0.000 0.008 ns 0.001 Genet M. et al. Ann. of Botany, in press
P.cembra.One year old needie 11111 30 54 200 入。8 Mar June July Aug Sept hu W2.Li MH 6 Month 02550m p四四和 。3200ma5 Abies 200 LEAF TEMPERATURE 出ML808ePa27a1a73793.1387 ag999 End of ain p/yoqn-UON 8
8 0 5 10 15 0 5 10 15 0 5 10 15 20 25 NSC(% d.m.) 0 5 10 15 0 5 10 0 5 10 10 15 Soluble sugars (% d.m.) 0 2 4 6 Previous‐year branches 0 2 4 6 8 Stem 0 2 4 6 8 Taproots 10 Coarse roots Starch (% d.m.) * * * * * * Figure 1. The seasonal variation (mean ± 1 SE) of total nonstructural carbohydrate (left panels), soluble sugars(middle panels), and starch (right panels) concentration for 10 tissues of Q. aquifoliodesshrubs growing at the three altitudes (3000 m, 3500 m, and 3950 m a.s.l.) in the Mt. Zheduo, SW China. Symbols: ○ = 3000 m a.s.l.; ■ = 3500 m a.s.l.; ∆ = 3950 m a.s.l.. 0 5 10 15 0 5 10 15 20 25 0 5 10 15 20 Apr May Jun Jul Aug Sep Oct Jan Apr Jul Oct 0 5 10 0 5 10 15 20 0 5 10 15 Apr May Jun Jul Aug Sep Oct Jan Apr Jul Oct 0 5 0 5 10 Medium roots 0 2 4 6 8 Apr May Jun Jul Aug Sep Oct Jan Apr Jul Oct Fine roots 2008 2009 2008 2009 2008 2009 Zhu WZ, Li MH (in preparation) * * * * * * ??? A winter carbon shortage? or An effect of phenological phase-shift? Hoch G. 2003 PhD thesis Uni. Basel Podocarpus oleifolius 2550 m a.s.l. 3200 m a.s.l. Espeletia neriifolia 2400 m a.s.l. 3200 m a.s.l. p Cavieres et al. 2000. Acta Oecologia 21, 203-211 5 10 15 20 25 30 Starch / Sugars / NSC concentration (% d.m.) Sugars Starch A B A B ** 1-yr-old needles 2-yr-old needles 3-yr-old needles Stem wood Fine roots Carbon shortage? - No! 0 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m 3750m 3300m April July April July April July April July April July Elevations of trees and sampling time Abies fabri Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387 Shi PL et al. 2006. Basic Appl. Ecol. 7(4), 370-377 End of winter r Mid season bohydrates + lipids wood (% d.m.) 0 2 4 4 NSC Lipids * * ** Pinus hartwegii Mexico (19° N) Pinus cembra Alps (46° N) Pinus sylvestris sylvestris Sweden (68° N) Late season Mid season Non-structural car structural ca in stem sap w Altitude 0 2 0 2 4 *** Low High Low High Low High G Hoch & C Körner (2003) Oecologia 135:10-21
30 G Hoch Ch Komer (2005)Funet Ecol 19.941-951 reux-du-Van.Swiss Jura Mts.1190r 10 5 9
9 30 40 50 ntrations (mg cm3) Branchwood Branchwood Stemwood Stemwood 120 160 200 Leaves ab b a a a a a a a Polylepis tarapacana, Volcano Sajama, Bolivia 30 40 50 Starch 0 10 20 NSC concen 4360 4550 4810 Elevation (m a.s.l.) 0 40 80 G Hoch & Ch Körner (2005) Funct Ecol 19, 941-951 4360 4550 4810 4360 4550 4810 0 10 20 Sugars c time (h) 20 30 ling time (h) 200 300 Mitotic time Cell doubling time 100 esis (%) Mitotic Temperature (°C) 0 10 Cell doub 0 100 0 10 20 30 40 Ch Körner (2003) Alpine Plant Life. Springer, Berlin 50 Net-photosynthe photosynth 1400 m a.s.l.. 1150 m a.s.l.. Air erature (｡C) 5 10 15 20 25 Creux-du-Van, Swiss Jura Mts, 1190 m Van, Swiss Jura Mts, 1190 m Picea abies Reference forest Dwarf forest Tempe 0 Year 2002 0 5 10 April May June July August Sept. October October 15 Soil Ch Körner, G Hoch (2006) Arct Antarct Alp Res 38, 113-119 Reference forest Dwarf forest Height / tree-ring growth of Pinus cembra trees (treeline vs. lower elevations) Li MH & Yang J, 2004. Ann. For. Sci. 61: 319-325 0 10 20 30 40 50 1971 1976 1981 1986 1991 1996 Year Tree ring width (0.1mm) 2080m 2040m 1990m 1970m 1910m
the s f Picea abies Larix decidua Each species is likely to respond to mate change in its own way: mountain slopes. .Elevaion (1970)Blevation (1952)Eeva Dupouey et al.1997 L2007.00-0●283-.187- 10
10 R2 = 0.86 R2 = 0.94 R2 = 0.27 0 10 20 30 40 50 60 5 10 15 20 25 30 35 Age of trees (years) Annual height increment (cm) 1680 m 1800 m 1940 m 1680 m 1800 m 1940 m 350 400 ) 1680m 1680 m Mean annual height increment and cumulative height of Picea abies trees growing at the treeline compared to lower R2 = 0.86 R2 = 0.98 R2 = 0.99 0 50 100 150 200 250 300 350 5 10 15 20 25 30 35 Age of trees (years) Mean height of trees (cm) 1680m 1800m 1940m 1940 m 1800 m compared to lower elevations in the Schmirn Valley, Austrian Alps. Li MH et al. 2003. Can. J. For. Res. 33, 653-662 R2 = 0.81 R2 = 0.64 R2 = 0.87 0 20 40 60 80 100 5 10 15 20 25 30 35 Age of trees (years) Annual height increment (cm) 1680m 1810m 1940m 1680 m 1810 m 1940 m 700 1680 Mean annual height increment and cumulative height of Larix decidua trees growing at the treeline compared Age of trees (years) R2 = 0.93 R2 = 0.98 R2 = 0.96 0 100 200 300 400 500 600 10 15 20 25 30 Age of trees (years) Mean height of trees (cm) 1680 m 1810 m 1940 m 1680 m 1940 m 1810 m treeline compared to lower elevations in the Schmirn Valley, Austrian Alps. Li MH et al. 2003. Can. J. For. Res. 33, 653-662 0 1 2 3 4 5 Tree ring width (mm) 1680 m 1800 m 1940 m 0 1 2 3 4 5 6 Tree ring width (mm) 1680 m 1810 m 1940 m Picea abies Larix decidua 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 Year 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 Year Mean tree ring width of trees growing at the treeline compared to lower elevations in the Schmirn Valley, Austrian Alps. Li MH et al. 2003. Can. J. For. Res. 33, 653-662 Location Authors, year Species Upword shift (m) Period (year) Rate (m/yr) South Island, New Zealand Wardle & Coleman, 1992 Nothofagus menziesii, N. solandri 7-9 1930-90 0.12-0.15 Italian Alps Leonelli et al. 2010 115 1901-2000 1.15 Glacier N.P. Montana Bekker, 2005 Picea engelmannii, Pinus contorta, Abies lasciocarpa 7-16 1800-1980 0.28-0.62 Sunwapta Pass, Alberta Luckman & Kavanagh, 2000 P. engelmannii, A. lasciocarpa 145 1700-1994 0.5 Uinta Mts. UT Munroe, 2003 P. engelmannii, A. lasciocarpa 61-183 1870-2001 0.5-1.4 SW Yukon Danby & Hik, 2007 Picea glauca 65-85 1920-2005 0.8-1.0 Scands Mts, Sweden Kullman, 2001 Betula pubescens, Pinus sylvestris, Picea abies 100-165 1915-2000 1.2-1.9 Kootenay NP, B.C. Roush, 2009 Larix lyallii, P. engelmannii, A. lasciocarpa 149 1909-1976 2.2-5.7 W. Himalayas of India Dubey et al. 2003 14-19 Over 10 yrs 1.4-1-9 Baima Snow Mt, Yunnan Baker & Moseley, 2007 67 Since 1923 Nanda Devi in C. Himalaya Panigrahy et al., 2010 300 Since 1960 Himalayas, Nepal Vijayaprakash & Ansari, 2009 Abies spectabilis N-aspect South-asp. 1.7 (N-s) 2.3 (S-s) Species No. Elevation (1970) Elevation (1992) Elevational shift (m) Vaccinium uliginosum 11 2216 2216 0 Each species is likely to respond to climate change in its own way: Vaccinium vitis-idaea 30 1898 1885 -13 Vaccinium myrtillus 31 1972 2002 30 Rhododendron ferrugineum 30 2098 2098 0 Pinus cembra 31 2064 2005 -59 Hieracium pilosella 13 1851 1930 79 Scleropodium purum 26 1425 1630 205 Dupouey et al. 1997 Species-specific treeline shifts (m) over different periods of time, separately for two mountain slopes. Kullman L, 2007. Geo-Öko 28 (3-4), 187-221